The virophages that Suttle found could also explain the origin of another strange genetic phenomenon. Transposons, or “jumping genes,” are DNA sequences that can move around within the genomes of living organisms. The DNA sequences of the virophages that Suttle and Fischer found were similar to those of a certain type of transposon called Polintons. Virophages are now known to infect giant viruses, which in turn infect host cells such as algae or amoebas. Suttle and Fischer hypothesized that this might have gone one step further in the past: Ancient virophages might have become part of the host cell over time as part of a mutually beneficial arrangement—the virophages killed attacking giant viruses for the host and got a safe place to hang out. Eventually, those virophages became transposons.
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Also, from Wikipedia:
"Sputnik was first isolated in 2008 from a sample obtained from humans; it was harvested from the contact lens fluid of an individual with keratitis.[5] Naturally however, the Sputnik virophage has been found to multiply inside species of the opportunistically pathogenic protozoan Acanthamoeba, but only if that amoeba is infected with the large mamavirus. Sputnik harnesses the mamavirus proteins to rapidly produce new copies of itself."